The present invention relates to the sensors for the detection of selected materials. More particularly, the present invention pertains to sensors for the detection of gas phase materials.
In the fabrication of integrated circuits, various layers of the same or different materials are used. For example, during the formation of semiconductor devices, such as dynamic random access memories (DRAMs), static random access memories (SRAMs), ferroelectric (FE) memories, etc., a variety of conductive and non-conductive materials are used to construct storage cell capacitors and also may be used in interconnection structures, e.g., conductive layers of contact holes, vias, etc.
These materials are typically supplied in a gas phase conducive to the formation of a film on a surface. When supplied in the gas phase, many of these materials may become toxic or otherwise harmful to health. As a result, it may be important to monitor where these materials are found and the concentrations in which they are found. Furthermore, because the effects may be cumulative, i.e., repeated exposure to low levels of the selected materials may be additive, it may be important to provide sensors and detection methods that are capable of measuring for cumulative exposure levels in addition to real-time exposure.
Semiconductor device manufacturing is one example of an environment in which the monitoring of exposure to potentially harmful materials can be advantageous. For example, various metals, metallic compounds, metal oxides, etc. are used to manufacture various structures used in semiconductor devices. A number of these materials may pose health risks based on exposure to the materials in the gas phase.
For example, ruthenium oxide and ruthenium have recently been employed in semiconductor devices because these materials are electrically conductive, conducive to conformal deposition, and they are easily etched. For example, the article entitled, xe2x80x9c(Ba,Sr)TiO3 Films Prepared by Liquid Source Chemical Vapor Deposition on Ru Electrodes,xe2x80x9d by Kawahara et al., Jpn. J. Appl. Phys., Vol. 35 (1996), Part 1, No. 9B (September 1996), pp. 4880-4885, describes the use of ruthenium and ruthenium oxide for forming electrodes in conjunction with high dielectric constant materials. It is, however, known that gaseous ruthenium tetraoxide (RuO4) is toxic at very low levels, e.g., about 1 part per billion (ppb). Monitoring of exposure to ruthenium tetraoxide is, therefore, both important due to its toxicity and difficult due to the low exposure levels at which the toxicity becomes an issue.
For example, many detection systems or procedures for many different gas phase materials rely on chemically sensitive tapes. Stains are produced due to chemical reactions occurring on the tapes in response to chemical exposure and those stains can then be detected. Problems with such tapes may, however, include sensitivity to different chemicals.
With respect to ruthenium tetraoxide, some useful chemically sensitive tapes are also sensitive to other chemicals such as oxidizing agents. As a result, the tapes typically cannot be used to accurately detect exposure to ruthenium oxide. Other tapes may detect ruthenium oxide, but could not be used to accurately detect at desired exposure levels.
The present invention provides sensors for and methods of detecting the presence of gas phase materials by detecting the formation of films based on the gas phase material. Advantageously, some gas phase materials preferentially deposit on receptor materials. As a result, selective detection of those gas phase materials can be obtained by detecting films deposited on the receptor materials. In addition to selectivity, the present invention may also provide for continuous film deposition on a receptor material at the minimum, or close to minimum, exposure levels.
Further advantages of the present invention are an increased sensitivity to the deposition of conductive materials through the use of closely spaced conductive electrodes interconnected by lines of receptor material. The gas phase material preferentially deposits on the receptor material as compared to the surrounding substrate surface. That preferential deposition may improve sensitivity of the sensor by reducing the areas on which the gas phase material will form conductive layers.
In one aspect, the present invention provides for detection of gaseous ruthenium oxide (RuO4) which preferentially deposits on a variety of surfaces, e.g., polypropylene. The deposited film includes elemental ruthenium (Ru) and/or ruthenium oxide (RuO2) which exhibit relatively high electrical conductivity. As a result, detection of gaseous ruthenium oxide may be performed by monitoring electrical conductivity across a detection surface. Exposure levels may be determined based on the increases in electrical conductivity.
Further advantages of the present invention may include reduced sensitivity to environmental contaminants because relatively few environmental contaminants will deposit on any surface in the form of, e.g., an electrically conductive film. In addition, heating the detection surface or otherwise treating the detection surface during or before use may further improve sensitivity to environmental contaminants by reducing or eliminating deposition of environmental moisture and most organic materials.
Detection of the selected material or materials in the gaseous phase may serve a variety of purposes including the detection of toxic/hazardous materials to insure proper industrial safety standards; to monitor reaction levels for process control; to determine the integrity of containment systems; etc.
In one aspect, the present invention provides a sensor array for detecting a gas phase material, the array including a substrate surface; at least one line of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the line of receptor material and opening in alternating first and second opposing directions along the line of receptor material; and a comb electrode on the substrate surface, the comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the line of receptor material.
In another aspect, the present invention provides a sensor array for detecting a gas phase material, the array including a substrate surface; at least two lines of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the lines of receptor material and opening in alternating first and second opposing directions along the lines of receptor material; and a comb electrode on the substrate surface, the comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the lines of receptor material.
In another aspect, the present invention provides a sensor array for detecting a gas phase material, the array including a substrate surface; at least one line of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the line of receptor material and opening in alternating first and second opposing directions along the line of receptor material; a first comb electrode on the substrate surface, the first comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the line of receptor material; and a second comb electrode on the substrate, the second comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the second direction, and further wherein at least some of the tines of the second comb electrode extending into the U-shaped segments intersect the line of receptor material.
In another aspect, the present invention provides a sensor array for detecting a gas phase material, the array including a substrate surface; at least two lines of receptor material on the substrate surface, wherein the selected material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the lines of receptor material and opening in alternating first and second opposing directions along the lines of receptor material; a first comb electrode on the substrate surface, the first comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the lines of receptor material; and a second comb electrode on the substrate, the second comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the second direction, and further wherein at least some of the tines of the second comb electrode extending into the U-shaped segments intersect the lines of receptor material.
In another aspect, the present invention provides a method of detecting a gas phase material by providing a sensor array including a substrate surface; at least one line of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the line of receptor material and opening in alternating first and second opposing directions along the line of receptor material; and a comb electrode on the substrate surface, the comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the line of receptor material. The method also includes exposing the sensor array to the gas phase material and monitoring electrical conductivity between the serpentine electrode and the comb electrode.
In another aspect, the present invention provides a method of detecting a gas phase material by providing a sensor array including a substrate surface; at least two lines of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the lines of receptor material and opening in alternating first and second opposing directions along the lines of receptor material; and a comb electrode on the substrate surface, the comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the lines of receptor material a substrate surface. The method also includes exposing the sensor array to the gas phase material and monitoring electrical conductivity between the serpentine electrode and the comb electrode.
In another aspect, the present invention provides a method of detecting a gas phase material by providing a sensor array including a substrate surface; at least one line of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a continuous serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the line of receptor material and opening in alternating first and second opposing directions along the line of receptor material; a first comb electrode on the substrate surface, the first comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the line of receptor material; and a second comb electrode on the substrate, the second comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the second direction, and further wherein at least some of the tines of the second comb electrode extending into the U-shaped segments intersect the line of receptor material. The method also includes exposing the sensor array to the gas phase material and monitoring electrical conductivity between the serpentine electrode and at least one of the first and second comb electrodes.
In another aspect, the present invention provides a method of detecting a gas phase material by providing a sensor array including a substrate surface; at least two lines of receptor material on the substrate surface, wherein the selected material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the lines of receptor material and opening in alternating first and second opposing directions along the lines of receptor material; a first comb electrode on the substrate surface, the first comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the lines of receptor material; and a second comb electrode on the substrate, the second comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the second direction, and further wherein at least some of the tines of the second comb electrode extending into the U-shaped segments intersect the lines of receptor material. The method further includes exposing the sensor array to the gas phase material and monitoring electrical conductivity between the serpentine electrode and at least one of the first and second comb electrodes.
In another aspect, the present invention provides a system for detecting a gas phase material, the system including a sensor array with a substrate surface; at least one line of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the line of receptor material and opening in alternating first and second opposing directions along the line of receptor material; and a comb electrode on the substrate surface, the comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the line of receptor material. The system further includes a detector in electrical communication with the serpentine electrode and the comb electrode.
In another aspect, the present invention provides a system for detecting a gas phase material, the system including a sensor array with a substrate surface; at least two lines of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the lines of receptor material and opening in alternating first and second opposing directions along the lines of receptor material; and a comb electrode on the substrate surface, the comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the lines of receptor material a substrate surface. The system further includes a detector in electrical communication with the serpentine electrode and the comb electrode.
In another aspect, the present invention includes a system for detecting a gas phase material, the system including a sensor array with a substrate surface; at least one line of receptor material on the substrate surface, wherein the gas phase material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the line of receptor material and opening in alternating first and second opposing directions along the line of receptor material; a first comb electrode on the substrate surface, the first comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the line of receptor material; and a second comb electrode on the substrate, the second comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the second direction, and further wherein at least some of the tines of the second comb electrode extending into the U-shaped segments intersect the line of receptor material. The system further includes a detector in electrical communication with the serpentine electrode, the first comb electrode and the second comb electrode.
In another aspect, the present invention provides a system for detecting a gas phase material, the system including a sensor array with a substrate surface; at least two lines of receptor material on the substrate surface, wherein the selected material preferentially deposits on the receptor material as compared to the substrate surface surrounding the receptor material; a serpentine electrode on the substrate surface, the serpentine electrode including a plurality of U-shaped segments spaced along the lines of receptor material and opening in alternating first and second opposing directions along the lines of receptor material; a first comb electrode on the substrate surface, the first comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the first direction, and further wherein at least some of the tines extending into the U-shaped segments intersect the lines of receptor material; and a second comb electrode on the substrate, the second comb electrode including a plurality of tines, wherein at least some of the tines extend into at least some of the U-shaped segments opening in the second direction, and further wherein at least some of the tines of the second comb electrode extending into the U-shaped segments intersect the lines of receptor material. The system further includes a detector in electrical communication with the serpentine electrode, the first comb electrode and the second comb electrode.
These and other features and advantages of the present invention are described below with respect to illustrative embodiments of the invention.